Casing for transporting a toner mixture and method for producing a casing of this type

ABSTRACT

A casing is provided for transport of a toner mixture on its outer surface in a development device. An outer surface of a metal casing is chemically pre-treated. In a subsequent chemical deposition, a nickel-copper-phosphor layer is generated on the outer metal casing surface. The layer comprises 1 to 2% copper and 8 to 10% phosphor and the remainder comprises substantially nickel.

BACKGROUND

The preferred embodiment concerns a casing for transport of a tonermixture on its outer surface in a toner development device, whereby thewall of the casing is substantially comprised of anelectrically-conductive material. The preferred embodiment also concernsa method for production of such a casing.

In electrographic printer or copiers, image development methods are usedthat develop the electrostatic charge images on surfaces (advantageouslyon photoconductor surfaces) via an air gap or in direct contact withtriboelectrically charged toner. The toner is frequently executed as atwo-component mixture made from toner particles and ferromagneticcarrier particles. This two-component mixture is transported with theaid of a casing on its surface, whereby this casing internally containsmagnets whose magnetic field, with the aid of carrier particles, forms amagnetic brush on the surface of the casing that transports the tonerparticles.

A casing for a toner development device on whose surface a two-componentmixture is transported is described from DE-A-2846430. In this document,it is viewed as a disadvantage that conventional casings use aluminum asa material in which eddy currents are generated due to the varyingmagnetic field, which eddy currents effect a heating of the tonermaterial and its softening. It is therefore proposed there to use amaterial with a high electrical resistance in order to reduce the eddycurrent effect. The casing is accordingly produced from a copper-nickelalloy and the generated surface of the casing is provided with groovesparallel to the axis.

Furthermore, casings for transport of a toner mixture are also used incleaning devices within a developing device. DE-A-10152892 gives anexample for this.

JP 03-041485 A with abstract, U.S. Pat. No. 6,201,942 B1, DE 33 03 167A1 and EP 0 800 336 A1 are as further prior art.

In practice, aluminum is conventionally used as a casing material.However, aluminum has the disadvantage that it is a relatively softmaterial whose surface wears in the course of time in printingoperation. It can thereby lead to quality losses in the print image. Inorder to provide the surface of the casing with a harder material, itwas proposed to provide the aluminum casing with a nickel layer on itssurface. This does in fact have the desired effect with regard to thehardness, however the electrical resistance of the entire casing ishereby altered, which leads to a negative influencing of theelectromagnetic properties on the surface of the casing.

A further problem in transport casings for toner is the oxidation on thetransport surface. Given aluminum casings, aluminum oxide can form onthe surface. The oxide layer likewise alters the properties of thecasing material, for example the electrical resistance, and thus theelectromagnetic parameters at the connection point of casing andphotoconductor drum.

SUMMARY

It is an object to specify a casing for transport of a toner mixture anda method for production of a casing, whereby important electromagneticand mechanical properties are achieved for the function.

A casing is provided for transport of a toner mixture on its outersurface in a development device. An outer surface of a metal casing ischemically pre-treated. In a subsequent chemical deposition, anickel-copper-phosphor layer is generated on the outer metal casingsurface. The layer comprises 1 to 2% copper and 8 to 10% phosphor andthe remainder comprises substantially nickel.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a hollow cylindrical casing for transport of toner; and

FIG. 2 and FIG. 3 illustrate method steps for production of the surfacelayer for the casing made from aluminum.

DESCRIPTION OF THE PREFERRED EMBODIMENT

For the purposes of promoting an understanding of the principles of theinvention, reference will now be made to the preferred embodimentillustrated in the drawings and specific language will be used todescribe the same. It will nevertheless be understood that no limitationof the scope of the invention is thereby intended, such alterations andfurther modifications in the illustrated device, and/or method, and suchfurther applications of the principles of the invention as illustratedtherein being contemplated as would normally occur now or in the futureto one skilled in the art to which the invention relates.

With the preferred embodiment a casing of the previously cited type isprovided wherein in that the outer surface of the casing receives alayer made of nickel-copper. On the one hand this alloy layer has therequired hardness and thus a lower abrasion, so that a higher usageduration results. On the other hand, such a layer has a high electricalconductivity, whereby advantageous electromagnetic properties result.The electrical resistance of this layer can be optimized via adjustmentof the alloy ratios. Such an alloy layer can only be slightly magnetizedor not magnetized at all, such that a disadvantageous residual magnetismis avoided. The combination of high electrical conductivity and highhardness leads to the situation that previous aluminum casings can beexchanged for the casing of the preferred embodiment withoutelectromagnetic or mechanical parameters being changed to a greatextent. An oxidation of the surface is avoided due to the alloy layer.

FIG. 1 shows a cylindrical casing 10 with a surface section A. Such acasing 10 can, for example, have a length L of 500 mm, an externaldiameter d of 60.5 mm, and an inner diameter of 56 mm. As is shown inthe surface section A, the surface can have a groove structure with theparameters a=0.45±0.05 mm, b=0.62±0.05 mm and c=0.5±0.2 mm. Thetransport behavior of the surface of the casing 10 is improved with aidof this groove structure.

The casing 10 is advantageously comprised of aluminum and bears a layermade of nickel-copper on its outer surface having a thickness in a rangeof 15 to 25 μm. This layer is generated via chemical deposition, wherebya chemical nickel-copper-phosphor deposition occurs. The layer typicallycontains 1 to 2% copper and 8 to 10% phosphor, whereby the remainder isnickel deposition.

Using a workflow diagram, FIGS. 2 and 3 show the chemical surfacetreatment for generation of the casing with the nickel-copper layer. Thealuminum casing is initially degreased in alkaline solution (step 20). Aflushing step 22 subsequently occurs. An etching in NaOH 30% occurs inthe subsequent step 24. A flushing step (step 26) subsequently occurs.

A cleansing in HNO₃, i.e. an etching in nitric acid 1:1, occurs in step28 after the alkaline etching. Because, depending on the materialcomposition, brown to black etching slurry forms on the surface afterthe alkaline etching, it is subsequently cleansed in nitric acid inorder to prevent the formation of AlO₃. A flushing step 30 subsequentlyoccurs in turn. An electrically conductive layer is applied in step 32in a zincate etching. The oxide layer on the aluminum material is alsoneutralized with the aid of this conductive layer. A flushing step 34subsequently occurs.

FIG. 3 shows the subsequent flushing step 36 with de-mineralized water,i.e. de-ionized water, from which all minerals have been extracted in anion exchanger. The surface is chemically pre-nickeled in the subsequentstep 38. An inhibitor wash occurs in the subsequent step 40. A flushingin a reservoir without water feed occurs in the inhibitor wash, wherebythe concentration in the wash increases. The content of the wash canthen be fed back into the chemical nickel bath or be otherwiseprocessed. Displacement losses are thus reduced. Cleansing in de-ionizedwater subsequently occurs in step 42.

The chemical deposition process subsequently occurs in step 44 with thenickel-copper-phosphor deposition that comprises a deposition of 1 to 2%copper, 8 to 10% phosphor and the remainder essentially a nickeldeposition. Flushing in de-ionized water subsequently occurs in step 48.A watering in 60° C. water subsequently occurs in step 48, whereby thenickel-plated parts remain in de-ionized water 2-3 minutes before thedrying. The finished casing is dried in hot air in the concluding step50.

An example for a bath preparation for nickel-copper-phosphor depositionin step 44 is reproduced in the following, whereby the composition isspecified in g/l:

nickel sulfate 30 g/l

copper sulfate 0.6-1.5 g/l

sodium hypophosphite 15 g/l

sodium citrate 50 g/l

ammonium chloride 40 g/l

pH value 9.0

temperature (° C.) 75

The casing so produced can be used as a transport casing for transportof a two-component toner mixture in development devices. The transportof toner can occur between rollers or also in the form of an applicatorelement in the immediate proximity of a photoconductor surface.Furthermore, such a casing can be used as a cleaning device.

Although a preferred exemplary embodiment is shown and described indetail in the drawings and in the preceding specification, it should beviewed as purely exemplary and not as limiting the invention. It isnoted that only the preferred exemplary embodiment is are shown anddescribed, and all variations and modifications should be protected thatpresently and in the future lie within the protective scope of theinvention.

1-10. (canceled)
 11. A casing for transport of a toner mixture on its outer surface in a development device, said casing having a wall substantially comprised of an electrically-conductive material, and an outer surface of the wall bearing a layer comprised of nickel-copper.
 12. A casing accordance to claim 11 in which the layer is generated via chemical deposition.
 13. A casing according to claim 12 wherein for said chemical deposition a chemical nickel-copper-phosphor deposition occurs.
 14. A casing according to claim 11 in which a thickness of the layer lies in a range of 15-25 μm.
 15. A casing according to claim 11 in which the wall of the casing is substantially comprised of aluminum.
 16. A casing according to claim 11 in which the toner mixture comprises a two-component mixture which comprises ferromagnetic carrier particles and toner particles.
 17. A method for production of a casing for transport of a toner mixture on its outer surface in a development device, comprising the steps of: chemically pre-treating an outer surface of a metal casing; and in subsequent chemical deposition generating a nickel-copper-phosphor layer on the outer surface of the metal casing, the layer comprising 1 to 2% copper and 8 to 10% phosphor and a remainder comprises substantially nickel.
 18. A method according to claim 17 wherein said metal casing comprises aluminum on which a conductive layer is applied in a zincate etching after the chemical pre-treating, a chemical pre-nickeling occurs thereupon, and said chemical nickel-copper-phosphor deposition then subsequently occurs.
 19. A method according to claim 17 in which a chemical bath which comprises nickel sulfate 30 g/l, copper sulfate 0.6 to 1.5 g/l, sodium hypophosphate 15 g/l, sodium citrate 50 g/l, and ammonium chloride 40 g/l is used for a chemical nickel-copper-phosphor deposition.
 20. A method according to claim 19 in which the bath has a pH value of 9.0 and a temperature of 75° C.
 21. A method for production of a casing for transport of a toner mixture on its outer surface in a development device, comprising the steps of: chemically pre-treating an outer surface of a metal casing; and in a subsequent chemical deposition generating a nickel-copper-phosphor layer on the outer metal casing surface, the layer comprising 1 to 2% copper and 8 to 10% phosphor and a remainder comprises substantially nickel. 